1. Field of the Invention
The present invention relates to a device for shaping and directing a jet of carburetted mixture delivered by a pneumatic injector, feeding a reciprocating internal combustion engine.
2. Description of the Prior Art
These engines are usually fed either by a carburetor, or by a direct or indirect injection of the liquid fuel.
In the first case, the prior mixture of air and fuel takes place appreciably upstream of the intake ports of the cylinders, which causes inhomogeneities both in the distribution of the fuel in the air and in the distribution of the mixture between the cylinders. These imperfections adversely affect the efficiency of the engine, since the mixture may be exhausted when the cylinder is scavenged by the mixture admitted (in particular in two stroke engines). Finally, control of the amount of fuel in the air becomes very delicate when the carburetion must be optimized with a view to saving energy and reducing pollutants.
Direct or indirect injection of the liquid fuel reduces the harmful effects of poor distribution between the cylinders and losses to the exhaust, and facilitates fuel control. It has however disadvantageous in that inhomogeneities of the mmixture are created in the cylinders, which may cause poor combustion, particularly at high speeds.
A third method is little used or not used at all in reciprocating engines, namely pneumatic injection. This process combines the advantages of direct or indirect liquid injection with those of carburetion. In fact, the fluid introduced is already a carburetted mixture, and distribution thereof may be independent for each cylinder and determined so as to minimize the losses to the exhaust.
In the prior art there exists no device for shaping a jet penetrating into a combustion chamber in which there already exists a certain movement, for example a swirling movement of the charge contained in this chamber. Examples of devices for obtaining an overall swirling movement of the charge area described in French patent FR-A-313 652 and FR-A-1 520 353, in the English patent GB-882 706 and in the U.S. Pat. No. 1,866,703.